The proposed research consists of two experiments which will determine the role of the adrenal gland in regulating luteinizing hormone (LH) release and seasonal breeding in sheep. The specific aims of this research are to (1) test the hypothesis that the adrenal gland provides a portion of the negative feedback signal regulating LH release in ewes, and (2) test the hypothesis that the adrenal gland is necessary for expression of seasonal anestrus in ewes. These hypotheses will be tested by studying the effects of photoperiod on patterns of LH release in ovariectomized, adrenalectomized ewes in the presence and absence of estradiol, and by studying the effect of adrenalectomy on onset of seasonal anestrus in ewes. Results of this research will provide a better understanding of the mechanisms regulating seasonal breeding, and provide insight into how the adrenal might influence reproduction.